Still for reclaiming solvents



Dec. 18, 1956 R. B. HOBSON, JR

STILL FOR RECLAIMING SOLVENTS 2 Sheets-Sheet 1 Filed Oct. 21. 1954 IN;'EN TOR. HmiS/Z B. H 04501772, Jr,

ATTORNEY Dec. 18, 1956 R. B. HOBSON, JR 2,774,727

STILL FOR RECLAIMING SOLVENTS Filed Oct. 21, 1954 2 Sheets-Sheet 2 BYNM? 14 4 AT TORNY United States Patent' STILL FOR RECLAIMING SOLVENTSApplication October 21, 1954, Serial No. 463,636 v 1 Claim. (CL 202-187)This invention relates to new and useful improvements in stills fordistilling or reclaiming and more particularly to stills'of the jackettype.

:In commercial dry cleaning, for example, the. liquid solvent employedfor cleaning becomes. fouled with oil, soap and the like which cannotreadily be removed by filtering. Furthermore, in known stills forreclaiming the solvent, the foul liquid or sludge has: been introducedinto the still and residue has been removed from the still throughopenings at the side and bottom of the stills, which is a diflicultoperation and the stills are tall tanks that require narrow doors andthe sealing of the doors in order to prevent leakage. stills fail toremove much of the solvent from the residue.

Known practices for reclaiming such solvents have in volved undulycomplex, expensive and unsafe apparatus, or have been only partlyacceptable due toexcessive foaming of the oil or other dirty componentof the liquid under normal pressure at boiling temperature. Fouling ofthe condensate and other disadvantages'frequently accompany theseconditions. 1 1:.

A prime object of the present invention is to' provide a still fordistilling or reclaiming filter sludge or still residue, which still isof a convenient height, relatively large diameter and open at the topfor the'convenient loading or removal of the sludge or residue. i

Another object of the invention is to provide a still for rapidvaporization of volatile substance at substantially atmospheric pressureand wherein foaming is controlled! to prevent its fouling thecondensate.

7 -.A-. further object of the invention is to provide a still oflthistype with a flat heatingsurface to produce a layer'of solvent or sludgeof uniform thickness. 7 Other objects of the invention are to provide astill of this type which requires a minimum of-maintenance and operatingattention, which can be operated by an unskilled-person'at very" smallcost, which has no moving parts to get out of order, which is highlyresistant to corrosion and is easily cleaned, which is easily installedand which meets all the requirements of regulating bodies. v A j: 1

his further proposed to'provide" a still for distilling and reclaimingwhich is simple and sturdy in construction and which can be manufacturedand sold at'a reasonable cost.

Other objects and advantages will be apparent from the description ofthe invention to follow taken in connection with the accompanyingdrawings in which- Figure 1 is a central vertical sectional vew of adistilling and reclaiming still embodying the invention, showing thesteam and water supply connections.

" 2,774,727 C Patented Dec. 18, 1956 Referring in detail to the drawing,the still or distilling unit comprises a hollow body formed with acylindrical shell 1 and with a dish-shaped plate 2 forming the bottomclosure. The body is completely open at the top but is provided with aremovable cover 3 having a flange 4 which engages the upper rim of theshell for sealing the top end. A handle 5 is secured to the center ofthe cover for lifting the same. The shell 1 and cover 3 are preferablyformed of spun stainless steel, and the dish-shaped bottom closure 2 isformed of heavy boiler plate steel. The adjacent edges of the shell 1and the bottom closure 2 are fastened by welding as indicated at 6.Spaced tubular legs 7 are'welded to the bottom closure for supportingthe still. As shown, the vaporizing and condensing chamber has adiameter substantially greater than the height thereof above said plate.

Moreover, the

A- flat plate 8 is disposed across the bottom closure 2 adjacent itsupper end and is fastenedto the bottom closure by a fillet weld joint 9,said plate 8 also extending transversely of the cylindrical body 1,thereby forming a vaporizing and condensing chamber 10 thereabove forholding liquid, and leaving a space therebelow constituting a .steamchest 11. Stay bolts 12 extending through aligned openings in the plate8 and bottom closure 2 are fastened in place by fillet weld joints 13for bracing the plate 8 and bottom. closure. The plate serves as a floorfor the vaporizing and condensing cham-. ber 10 and is heated by steamsupplied to the steam chamber or chest 11 by an inlet pipe 14 anddischarged through a condensate outlet pipe 15. .Steam inlet pipe 14 isprovided with the usual gage 16 and pressure regulator 17.

Midway the height of the vaporizing and condensing chamber 10, a flangedcondensate collector ring 18, formed of angle bar, is disposed close tothe inner surface of the shell 1, with its flange 19 arrangedhorizontally and welded to the shell'as indicated at 20. The ring formsa narrow trough 21 between the ring and the inner surface of the shell1, with the flange 19 serving as the floor thereof.

An upright pipe 22 is connectedat one end to the steam inlet pipe 14 bya T-fitting 23 and at its other end to a horizontally disposed inletpipe 24 by an elbow fitting 25. The inlet pipe 24 extends through athreaded coupling 26 welded to the shell 1 and through an alignedopening 27 in the shell just below the condensate collector ring 18. Asteam sweep or injector device 28 is fastened on the inner end of theinlet pipe 24 close to the inner surface of the shell. The steam sweepmay haveva fan-shaped outlet end 29 directed circumferen- 1 tially ofthe shell 1. A valve'30 is interposed in the Figure 2 is a perspectiveview of the still on a reduced steam sweep looking in the direction ofthe arrows on the line 4-4 of Figure 3.

upright pipe 22. v

' Above the collector ring 18, a cooling deviceor condenser in the formof coils 31 is supported by means of spacedwire brackets 32 spacedaround the ring, each bracket having one end hooked through an openingin the ring as indicated at 33 and having its other end loopedaround-the condenser coils as indicated at 34 for supporting thecondenser above andin'lin'e with the trough 21. One end of the condenseris connected to a water inlet pipe 35 and the other end to a wateroutlet pipe 36. The inlet pipe 35 is connected to a water supply pipe 39and the water outlet pipe 36 is connected to a discharge pipe 40. Thesupply pipe 39 and the discharge pipe 40 may be provided withthermometers 41 and 42, respectively.

An outlet or discharge pipe 43 communicates with the condensate troughllbehind the ring 18 through an opening 44 in the shell. The outer end ofpipe 43 is removably connected through an elbow fitting 45 and a nut 46with a vertically disposed pipe 47 on the out- 3 side of the still, theother end 48 thereof being curved and connected to and supporting aseparating unit in the form of a U-shaped or looped pipe 49. Pipe 49 isvertically disposed with its open ends directed upwardly. One leg 59 ofthe U-shaped pipe is provided with a branch pipe 51 above its connectionwith the pipe 47, and the other leg 52 is provided with a similar branchpipe 53 above the branch pipe 51. Branch pipe 51 may be connected to apipe leading to the main tank (not shown), and branch pipe 53 may beconnected to a water drip line leading to a bucket or the like (notshown).

Theunit may be used for reclaiming liquid, such as perchlorethylene,from filter sludge orfrom'still residue. The filter sludge or stillresidue is loaded into the unit and onto the flat plate 8 through theopentop, If filter sludge is being treated, it is preferably previouslydampened and is normally piled about 4" deep on the plate 8, orapproximately half-way from the plate 8 to the condensate trough 21.Still residue is normally treated in batches of approximately three toten gallons.

In operation, the legs 7 support the hollow body 10 on a floor or thelike with the open top at a convenient height to permit sludge or stillresidue to be dumped into the body through said open top by anoperatorstanding on the floor. After the filter sludge or still residue to bevaporized is loaded onto the platev8, the steam and water are turned on.After the steam has been on for the desired length of time, usually anhour in the case of filter sludge and usually ten minutes in the case ofstill residue, the steam sweep 28is opened by means of the valve 30,just enough in the case of filter sludge to create a swirling circularcloud, and just cracked open in the case of still residue. The unit isnow operating for the length of the run, the time of which depends onthe amount of sludge or residue and the amount of perchlorethylene init. During this operation,vthe rising vapors of perchlorethylene will becondensed by the condensing coils 31 and the condensate collected in thetrough 21 and will be drained oil? through the outlet pipe 43. Thecondensate will be separatedv in the U-shaped pipe 49 and the solventdischarged through branch pipe 51 to the machine tank, and the waterthrough branch pipe 53 to the drip line leading to a bucket or the like.The unit is permitted to run until the recovery rate reaches nearly zeroat which time the steam sweep, the steam supply and the water supply areshut off. The .unit is permitted to cool off and the cap 54 on the drainfitting 55 provided on the-still is removed and the residue drained otfinto a suitable container and discarded.

The still may also be provided with a fitting 56 adjacent the plate 8for a. glass gauge and a fitting 5 7 adjacent the ring 18 for, anotherglass gauge.

The size and shape of the plate 8 .are such that a. large flat heatingsurface is provided whereby the matter may be loaded thereon in thinlayers which have a diameter many times greater. than their thicknessand may be eifectively treated. If the matter is in powdered form, theplate serves as a frying pan and in effect fries the volatile solventout of the powdered matter. When liquid is being treated, the largeheating surface provided by the plate compared to the depth of theliquid affords efiective distillation.

Instead of feeding the solvent to the unit inbatches, it will beunderstood that it may be fed automatically and continuously under thecontrol of an outside float.

A still embodying the structural features above described and as shownin the drawings requires in its construction only ordinary assemblingskill and a minimum of hand work compared to known stills of equivalentcapacity for a similar purpose. It operates at substantially atmosphericpressure in all parts, is economical in concentrating heat on thevaporizing plate and requires no skilled attention either for results orfor safety.

In distilling according to the method hereinabove disclosed, the largesurfaces atforded by the plate and shell and the amount of liquid on theplate permit very rapid and effective vaporization with substantially nowasted heat, no accumulation of vapor pressure above the liquid and nofouling of the condensate or other undesirable result from foaming.

It will be understood that changes in details of construction might bemade without departing from the scope and principle of the invention,and it is desired to be limited only by the state of the prior art andthe appended claim.

I claim:

A still for reclaiming a liquid solvent comprising a hollow cylindricalbody open at the top and having means at its bottom to set on a floor, asteam chest at the lower end of said hollow cylindrical body includingan approximately fiat plate extending transversely of said cylindricalbody throughout the cross-sectional area thereof, said plate and thewall of said body forming a vaporizing and condensing chamber having adiameter substantially greater than the height thereof above said plate,a condensate collector trough disposed above said plate and spaceddownwardly from the top of said body-and extending along the innersurface of the side wall of said cylindrical body, a condenser coilabove said condensate collector trough and closely adjacent the sidewall of said body, an outlet pipe extending from said condensatecollector trough outwardly from said body, a cover for said open top toprovide for easy and quick dumping of liquid or sludge through said opentop onto said plate in a layer below said condensate collector troughand for removal of said liquid or sludge from the body, and a steaminlet pipe below said condensate collector trough and above the level ofthe top surface of such layer having an outlet extendingcircumferentially of the body adjacent the side wall of the body anddownwardly toward said plate to provide a blanket cloud of steamswirling or rotating circumferentially of said body over the top surfaceof the layer of sludge or liquid on said plate. r

References Cited in the file of this patent,

UNITED STATES PATENTS 1,355,934 Bannon et al Oct. 19, 1920 1,938,604Mobley Dec. 12, 1933, 2,254,867 BonOttO Sept. 2,.1941 2,385,564 I Boothet al Sept. 25, 1945 2,504,053 Sweeney et al Apr. 11, 1950

